1. Field of the Invention
The present invention relates to an antenna unit having a plurality of antenna portions capable of receiving radio waves of frequency bands different from each other.
2. Description of the Related Art
In a conventional art, a rod antenna for receiving AM/FM radio waves is attached to a circuit board for functioning the antenna via an attaching member having conductivity. Up to the present date, in such a configuration, there has been proposed various antenna structures for achieving further excellent performance (for example, JP-A-2000-124722). According to JP-A-2000-124722, an antenna unit is configured by inserting an attaching member to a circuit board in a state of being brought into contact with a rod antenna.
In recent years, it is conceived to execute transmission and reception using various radio waves other than AM/FM radio waves in, for example, a vehicle-mounted apparatus and in accordance therewith, there are also needed plural kinds of antenna elements provided at the vehicle-mounted apparatus. According to the transmission and reception using radio waves, mentioned here, there are reception of GPS radio wave used for a navigation apparatus, data transmission and reception in an ETC apparatus, transmission and reception in satellite broadcast, and transmission and reception of data by Bluetooth (registered trade mark) standard, some of them are being used, and with regard to some of them, research and development for practical use had been carried out. Frequencies of the radio waves are higher than those of AM/FM radio waves and therefore, elements for receiving the radio waves are shorter than that of the above-described rod antenna.